Okay, let's tackle this question. The patient has loss of sensation at the angle of the mandible and the parotid area. I need to figure out which nerve is involved here.

First, I remember that the trigeminal nerve (CN V) is responsible for facial sensation. It has three branches: ophthalmic (V1), maxillary (V2), and mandibular (V3). The mandibular division is the largest and innervates the lower face. The angle of the mandible is a key area here.

The parotid area is also part of the face. The parotid gland is located in front of the ear and extends down to the angle of the jaw. The auriculotemporal nerve, a branch of the mandibular division of the trigeminal nerve, provides sensory innervation to parts of the parotid gland. Additionally, the auriculotemporal nerve also supplies sensation to the temporoparietal region and the external ear.

So, if there's a loss of sensation in the angle of the jaw and parotid area, the auriculotemporal nerve is likely affected. Let me check the options again. The correct answer should be the auriculotemporal nerve.

Wait, other branches of the mandibular nerve include the buccal nerve, which innervates the buccal mucosa and cheeks, and the lingual nerve for the anterior two-thirds of the tongue. The inferior alveolar nerve is a branch of the mandibular nerve but is more involved in the lower teeth and the chin. So, the auriculotemporal nerve fits the described areas.

I should make sure there's no confusion with other nerves. The facial nerve (CN VII) controls facial muscles but not sensation. The glossopharyngeal nerve (CN IX) is involved in the pharynx, not the face. The hypoglossal nerve (CN XII) is for tongue movement. So the answer must be the auriculotemporal nerve.

**Core Concept**
The question assesses knowledge of trigeminal nerve (CN V) anatomy, specifically the sensory distribution of its branches. The auriculotemporal nerve, a branch of the mandibular division (V3), innervates the parotid area and the angle of the mandible.

**Why the Correct Answer is Right**
The auriculotemporal nerve arises from the mandibular division of the trigeminal nerve (V3). It provides sensory innervation to the temporoparietal skin, external auditory meatus, and parotid gland. Injury to this nerve would result in sensory loss over the parotid region and the angle of the mandible, aligning with the clinical scenario described.

**Why Each Wrong Option is Incorrect**
**Option A:** If the buccal nerve were injured, sensation loss would occur in the buccal mucosa and cheeks, not the parotid area.
**Option B:** The lingual nerve, a branch of V3, innervates the anterior two-thirds of the tongue and is unrelated to the parotid region.
**Option C:** The facial nerve (CN VII) controls facial muscles and taste on the anterior tongue but does not mediate general sensation in the described

✓ Correct Answer: D. Greater auricular nerve